/*
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import java.util.HashMap;
import java.util.Map;

/**
 * A mutable class-to-instance map backed by an arbitrary user-provided map. See
 * also {@link ImmutableClassToInstanceMap}.
 * 
 * @author Kevin Bourrillion
 * @since 2010.01.04 <b>stable</b> (imported from Google Collections Library)
 */
public final class MutableClassToInstanceMap<B> extends
        ConstrainedMap<Class<? extends B>, B> implements ClassToInstanceMap<B> {

    /**
     * Returns a new {@code MutableClassToInstanceMap} instance backed by a
     * {@link HashMap} using the default initial capacity and load factor.
     */
    public static <B> MutableClassToInstanceMap<B> create() {
        return new MutableClassToInstanceMap<B>(
                new HashMap<Class<? extends B>, B>());
    }

    /**
     * Returns a new {@code MutableClassToInstanceMap} instance backed by a
     * given empty {@code backingMap}. The caller surrenders control of the
     * backing map, and thus should not allow any direct references to it to
     * remain accessible.
     */
    public static <B> MutableClassToInstanceMap<B> create(
            Map<Class<? extends B>, B> backingMap) {
        return new MutableClassToInstanceMap<B>(backingMap);
    }

    private MutableClassToInstanceMap(Map<Class<? extends B>, B> delegate) {
        super(delegate, VALUE_CAN_BE_CAST_TO_KEY);
    }

    private static final MapConstraint<Class<?>, Object> VALUE_CAN_BE_CAST_TO_KEY = new MapConstraint<Class<?>, Object>() {
        public void checkKeyValue(Class<?> key, Object value) {
            cast(key, value);
        }
    };

    public <T extends B> T putInstance(Class<T> type, T value) {
        return cast(type, put(type, value));
    }

    public <T extends B> T getInstance(Class<T> type) {
        return cast(type, get(type));
    }

    // Default access so that ImmutableClassToInstanceMap can share it
    static <B, T extends B> T cast(Class<T> type, B value) {
        // TODO: this should eventually use common.primitives.Primitives.wrap()
        return wrap(type).cast(value);
    }

    // safe because both Long.class and long.class are of type Class<Long>
    @SuppressWarnings("unchecked")
    private static <T> Class<T> wrap(Class<T> c) {
        return c.isPrimitive() ? (Class<T>) PRIMITIVES_TO_WRAPPERS.get(c) : c;
    }

    private static final Map<Class<?>, Class<?>> PRIMITIVES_TO_WRAPPERS = new ImmutableMap.Builder<Class<?>, Class<?>>()
            .put(boolean.class, Boolean.class).put(byte.class, Byte.class)
            .put(char.class, Character.class).put(double.class, Double.class)
            .put(float.class, Float.class).put(int.class, Integer.class)
            .put(long.class, Long.class).put(short.class, Short.class)
            .put(void.class, Void.class).build();

    @SuppressWarnings("unused")
    private static final long serialVersionUID = 0;
}
